: a polyhedron with two polygonal faces lying in parallel planes and with the other faces parallelograms
: a transparent body that is bounded in part by two nonparallel plane faces and is used to refract or disperse a beam of light
: a crystal form whose faces are parallel to one axis; especially: one whose faces are parallel to the vertical axis
Piece of glass or other transparent material cut with precise angles and plane faces. Prisms are useful for analyzing and refracting light (seerefraction). A triangular prism can separate white light into its constituent colours by refracting each different wavelength of light by a different amount. The longer wavelengths (those at the red end of the spectrum) are bent the least, the shorter ones (those at the violet end) the most. The result is the spectrum of visible light, or the rainbow. Prisms are used in certain kinds of spectroscopy and in various optical systems.